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SHORTWAVE
(HF)
RADIO STANDARD TIME SIGNALS

Short Wave radio -
traditionally our
timing "workhorse"
Short Wave Radio Standard Time signals have long been a favourite tool
for
scientific workers and observers at field sites, where medium accuracy
time
is needed, to be recorded continuously. At times of good radio
propagation,
any simple radio with a SW band can be used to pick up a usable
signal.
In addition to time pips, the SW signal usually also gives voice or
coded
time (Hour and Minute) information and station ID. The most
suitable
source of standard time signals in the South Pacific is WWVH,
broadcasting
from Hawaii.

An interesting note on the 'as
received' accuracy
of time signals, far away from their transmitter site, can be found in
this
archived post by Art Lucas
on the IOTA Occultations email group at: http://groups.yahoo.com/group/IOTAoccultations/
In practice, the WWVH signal from Hawaii can be used for (visual,
manual) basic timing tasks as far away as Australia with a propagation
delay of the
order of 0.05 second (approx. 50 ms).

Also see the note
below on a local group in New Zealand with interest in
time
on HF

In MemoriamVNG (Australia) died on
31
December 2002 at 23:43:43 UTC

VNG was inaugurated by the Australian Post Office on 21
September 1964 at Lyndhurst, Victoria, and operated on 4.500, 7.500 and
12.000 MHz until 1 October 1987, when transmissions were
terminated. It was then moved to Llandilo, New South Wales, where
the first transmission took place in June 1988. The service from
Llandilo continued until 31 December 2002. In the last period of
operation, standard time signals were available on 5.000, 8.638, 12.984
or 16.000 MHz
(daytime only) short
wave. A full description of the later Station, its history and
details
of
broadcast codes and format can be found in National Standards Commission information
leaflet
"Radio VNG".) If you would like to hear
the
last minute of VNG transmission on 12.984 MHz, please
check this MP3 sound file.
The last
second marker was at 23:43:43 UTC

When VNG was still available, the receiving equipment could be any
cheap old analogue (second hand shop) battery operated portable.
Since the
closure of VNG on 31 December 2002, the SW time signals available in
the
South Pacific have to travel from Hawaii, mainland USA, Canada or
China. The received signal strength in New Zealand and Australia
is lower and more
variable than that from VNG, making reliable reception more
difficult. In good conditions, however, the WWVH signal strength
can still be remarkably good for a few hours. To improve the performance of your receiver,
it is worth experimenting with long and short extension aerials.
Try different antenna compass orientations, and stay
away from power and cable TV cables and electric fences, all known
sources
of noise and interference. Short Wave radio can still be a
useful,
adequate, low cost entry point into fairly respectable timing.

WWVH (Hawaii) and WWV (Colorado)
WWVH and WWV broadcast on the international time standard frequencies
of
2.5, 5, 10, 15 and 20 (WWV only) MHz. In
New
Zealand and Australia 5 and 10 are the best at night, 10 and 15 (on
rare
occasions also 20 MHz) in the daytime and early evening. Mostly,
WWVH
is received at the best signal strength, with WWV faintly in the
background,
but at times WWV is almost as good. WWVH is a extremely
reliable and respected service. The Hawaiian service started in
1948 and between 2000 and 2007 a full set of new technology fibreglass
encased antennas was built on Kauai, suggesting that the service is to
continue for the coming years.

(Currently, in 2002, there appears to be a severe interference
problem
in Western
Australia with many Indonesian fishing vessels using 10 MHz as their
communication
channel, ignoring international regulations. This "chatter" is
noticeable
as far as South Eastern Australia, but WWVH is mostly still "usable"
there.)

On WWVH and WWV the seconds pulses are heard
every
second except on the 29th and 59th seconds of each minute. The first
pulse
of each hour is a long 800 ms pulse of 1500 Hz. The first pulse of each
minute
is a long 800 ms pulse of 1000 Hz at WWV and 1200 Hz at WWVH. The
remaining
seconds pulses are very short audio bursts (5 ms pulses of 1000 Hz at
WWV
and 1200 Hz at WWVH) that sound like the 'ticking' of a clock

The voice time announcements (female for WWVH, male for WWV) are
just before
each minute, other space and earth weather information, geophysical
alerts and GPS satellite status reports are broadcast at
set
times. For timekeeping ignore the ongoing continuous tones on
WWV/WWVH
which are often heard from second 1 (i.e. the tones start one second
after
the full minute) until second 45. The complete format
descriptions
of the WWVH and WWV time codes can be found at the NIST web site:
http://www.boulder.nist.gov/timefreq/

Because the signals from WWVH and WWV
are
often weak, there is a likelihood of interference from other standard
time
stations on the same international frequencies of 5, 10 and 15
MHz.
Most of these are no problem, because they also transmit UTC and are
usually
much weaker. One of these is standard time station ‘BPM’ in
Pucheng,
China, which is operated by the Chinese National Time Service Center
(NTSC)
(Shaanxi Astronomical Observatory, Chinese Academy of Sciences).
Like
other standard time signal stations, most of the time BPM transmits
UTC.

However, during the minutes 25 - 29 and 55 - 59, station
BPM
transmits UT1. Ref: Time Signal Stations Frequency
List
by Klaus Betke. This is a complex issue, because the
difference
(DUT1) between UT and UT1 can be positive or negative, and can be up to
0.9
sec. As a result, the BPM UT1 'pips' can be before or after the
WWVH
UTC 'tics'. If you encounter this problem with these two
stations,
then luckily they can be separated because the WWVH and WWVH second
markers
are 'ticks', and the BPM pips are 'beeps'. At present (January
2009)
DUT1
is about 0.4 seconds. Check this NIST web site for up to date
information: http://www.boulder.nist.gov/timefreq/pubs/bulletin/leapsecond.htm

The identity of station BPM can be confirmed by listening
during
the last minute of the hour, just before the full hour, when a female
(Chinese) voice speaks the words: "B P M ,..... B P M ,..... B P M
,.....". And, to confirm this further, the 'double' pips
should disappear on the half
or full hour. Repeat: this paragraph only applies to the UT1
pulses
during minutes 25 - 29 and 55 - 59.

To overcome this problem, try one of the other WWV(H)
frequencies.

CHU (Ottawa, Canada)
At times, on the 'non-standard' frequencies of 3.300, 7.850 and 14.670
MHz,
Canadian Standard Time Signal Station 'CHU' can also be received for a
few
hours in the South Pacific. NOTE: 7.850 MHz is a new
frequency that is being used as of January 1, 2009. The
old
frequency of 7.335 Mhz was within the expanded 40 metre international
broadcast band (7.200 - 7.350 MHz) as decided by the International
Telecommunication Union (ITU) in 2007. Indeed 7.850 has been
heard in South-Eastern Australia in early January 2009, but it is found
that WWVH on 5.000 is stronger at those times.

On CHU the 29th and 51st to 59th Second Markers
are omitted, and alternating bilingual voice announcements of local
time
(not UTC) are made between seconds 50 and 59. There are further
complex
time codes built into this signal between seconds 31 and 90 - for
details
see the Klaus Betke site. However, we find that: if CHU is
present,
WWVH or WWV are most likely stronger, and preferred for their easier to
read
time code system. Also Hawaii (the source of WWVH) is closer to
New Zealand and Australia than Ottawa, so that there is less
propagation delay.

POSSIBLE
INTEREST IN HF TIME DISTRIBUTION IN NEW ZEALAND

An amateur radio group in New Zealand has access to very
respectable time generating and low power HF transmitting
equipment.

which is maintained by Murray Greenman
ZL1BPU Please contact Murray directly for
technical enquiries, expressions of interest
and offers of support.

REGULAR
BROADCAST
'ON THE HOUR' TIME PIPS

For Domestic FM / AM radio stations in New
Zealand
and Australia:
Please follow this link to the Broadcast
Page

Do not use time pips on International SW
broadcast stations (e.g. the BBC)
Do not rely on time signals on large International SW broadcast
stations (e.g.
the BBC, RN, DW), which broadcast time pips on the full hour. The
problem
is that these SW (HF) broadcast programmes are distributed around the
world
using extremely long paths and variable networks that often include
satellite
links which add very large delays. As received, they can be
significantly
delayed. An exception is
Radio New Zealand International
(RNZI), as this only has one local transmitter. The signal from RNZI is
therefore
similar to that from the regular NZ
National Radio - please refer to the notes there.